1. Field of the Invention
The present invention relates to a textile printing technique using an ink-jet system.
2. Related Background Art
At present, textile printing is principally conducted by screen printing or roller printing. Both methods are unfit for multi-kind small-quantity production and unsuited to quickly cope with the fashion of the day. Therefore, there has recently been a demand for development of an electronic printing system making no use of any plate. In compliance with this demand, many textile printing processes according to ink-jet recording have been proposed. Various fields expect much from such textile printing processes.
As necessary conditions required for ink-jet textile printing, may be mentioned the following:
(1) being able to achieve sufficient color depth upon coloring with ink; PA1 (2) being able to provide a print high in color yield of dye on cloth and free from staining on white areas, and to conduct waste water treatment after completion of washing with ease; PA1 (3) causing little irregular bleeding due to color mixing between inks of different colors on cloth PA1 (4) being able to achieve color reproduction within a wide range; and PA1 (5) being able to achieve stable coloring upon fixing treatment. PA1 (a) successively applying, as ink droplets, at least two inks of different colors to a cloth to form a color-mixed portion; PA1 (b) subjecting the cloth to a heat treatment to fix dyes contained in the inks to the cloth; and PA1 (c) washing the cloth to remove unfixed dyes from the cloth, PA1 (a) successively applying, as ink droplets, at least two inks of different colors to a cloth to form a color-mixed portion; PA1 (b) subjecting the cloth to a heat treatment to fix dyes contained in the inks to the cloth; and PA1 (c) washing the cloth to remove unfixed dyes from the cloth, wherein the inks comprise water, an organic solvent and individual reactive dyes different from each other in reaction rate, and the dye content per droplet of the ink containing a slower-reacting dye is made lower. PA1 (a) successively applying, as ink droplets, at least two inks of different colors to a cloth to form a color-mixed portion; PA1 (b) subjecting the cloth to a heat treatment to fix dyes contained in the inks to the cloth; and PA1 (c) washing the cloth to remove unfixed dyes from the cloth, PA1 (a) successively applying, as ink droplets, at least two inks of different colors to a cloth to form a color-mixed portion; PA1 (b) subjecting the cloth to a heat treatment to fix dyes contained in the inks to the cloth; and PA1 (c) washing the cloth to remove unfixed dyes from the cloth, PA1 (a) successively applying, as ink droplets, at least two inks of different colors to a cloth to form a color-mixed portion; PA1 (b) subjecting the cloth to a heat treatment to fix dyes contained in the inks to the cloth; and PA1 (c) washing the cloth to remove unfixed dyes from the cloth, PA1 (a) successively applying, as ink droplets, at least two inks of different colors to a cloth to form a color-mixed portion; PA1 (b) subjecting the cloth to a heat treatment to fix dyes contained in the inks to the cloth; and PA1 (c) washing the cloth to remove unfixed dyes from the cloth, PA1 (1) the volume of a droplet of the ink being made smaller; PA1 (2) the dye content per droplet being made lower; PA1 (3) the organic solvent content per droplet being made lower; PA1 (4) the pH of the ink being higher within a range of from 4 to 10; PA1 (5) the ink being applied earlier to a cloth; and PA1 (6) the surface tension of the ink being made lower. It has also been found that even if fixing conditions vary to some extent, coloring ability does not differ much, so that prints can be obtained stably. This means that the influence of difference in reaction rate between the reactive dyes contained in the individual inks, said difference being the main reason that the above-described requirements are not satisfied by the conventional printing processes, is eliminated. PA1 (R: reflectance at a maximum absorption wavelength).
In order to satisfy these requirements, it has been principally conducted to add various additives to ink or to subject cloth to pretreatment. However, such methods have failed to satisfy all the above requirements at the same time.
As an illustrative method for satisfying the requirement (3) though it is not applied to cloth, may be mentioned a method in which shot of inks is conducted in particular order of lightness, as described in Japanese Patent Application Laid-Open No. 62-161541. In the case of cloth, it is however impossible to satisfy the requirement (3) because color yields of inks making use of reactive dyes vary depending upon their reaction rates when the inks are shot on the cloth in order of initial lightness inherent in each ink.
Further, the textile printing requires a fixing process and, as a final step, a washing process in which unfixed dyes attached to cloth are removed. It is therefore necessary to handle in a manner different from that in conventional recording on the common paper so as to cope with the requirement (2) described above.
In particular, in the case of ink-jet textile printing, the amount per unit area of dyes applied to cloth is less than in conventional textile printing processes. Therefore, a delicate difference in conditions in the fixing process greatly affects coloring ability, resulting in raising many problems. For example, when an image is formed with at least two inks containing separately dyes different in reaction rate, a state that a fixed dye and an unfixed dye coexist appears in the course of the fixing process. At this time, if fixing conditions are preset on the basis of the ink containing a slow-reacting dye, bleeding becomes marked, and flushing and deterioration in level dyeing ability are caused at color-mixed portions. On the contrary, if the conditions are preset on the basis of the ink containing a fast-reacting dye, reduction in color yield, staining on white area and deterioration in color depth are caused.
In order to cope with the above problem, it is considered to conduct ink-jet textile printing with at least two inks separately containing dyes equal in reaction rate, thereby permitting the optimum presetting of fixing conditions so as not to cause the problems of color yield, coloring ability, level dyeing ability and bleeding. Actually, however, the formation of images is often conducted with at least two inks separately containing dyes different in reaction rate. With respect to the requirement (5) that stable coloring must be achieved, in particular, in the case where textile printing is conducted by an ink-jet system, there is accordingly a demand for technical improvement peculiar to its printing process.
As described above, means capable of satisfying one of the above requirements to some extent have been able to be found in the prior art. However, there has not yet been known any ink-jet printing process which can satisfy all the above-mentioned requirements at the same time, solve all the problems relating to such requirements, and stably provide images of the best quality.
In addition, the conventional processes making use of a textile size, such as screen printing and roller printing use great amounts of dyes because the color yield of the dyes is low. As a result, the outflow of the dyes in a washing process causes environmental pollution, and staining on white areas in the washing process becomes a problem awaiting solution.